For example, a study confirmed elevated levels of both pro- and anti-inflammatory cytokines (including IFN-γ, IL-1ra, IL-10, IL-18, MCP-3, M-CSF and G-CSF) in COVID-19 patients, while no changes in various cytokines (including T helper 2 cell-related cytokines IL-4, IL-5, and IL-10) or lymphocyte subset distribution before and after vaccination were observed (58, 59). Here, IL18 is linked to COVID-19.